1. Field of the Invention
This invention concerns oil filters for cooking oil. More specifically, it is directed to a dual filtering apparatus which in a first stage removes contaminant particles having diameters greater than about 20-25 microns, and in the second stage removes smaller particles down to the size of about 0.1 micron.
2. Discussion of the Background of the Invention
The background of the invention is discussed in greater detail in application Ser. No. 432,009 filed Sept. 30, 1982, U.S. Pat. No. 4,517,082, which has been incorporated by reference.
The present invention employs a dual filtering system, the first stage of which removes contaminant particles greater than 25 microns in diameter while the second stage removes particles between 0.1 and 25 microns. The first stage employs suction filtration while the second stage utilizes positive pressure which more effectively forces the oil through a denser filtering media than would be possible with suction filtration.
This invention is particularly suited for restaurants and fast food outlets which cook foods in vats filled with oil for deep fat frying after covering the food with large amount of flour. When the food coated with the flour is placed into the cooking oil, the oil removes some of the flour from the surface of the food, the flour chemically interacts with the oil under conditions of high heat, and flour decomposition occurs. This decomposition results in contaminant particles which affect food taste and reduces the usable life of the cooking oil because the particles give off gases that break down the molecular structure of the cooking oil. The ultimate result is a food product which is soggy and without a firm crust, the taste and texture of the food having been spoiled.
It is an object of the invention to remove contaminant particles from cooking oil to prolong the usable life of the cooking oil by removing contaminant particles that accelerate decomposition of the cooking oil.
It is a further object of the invention to provide a portable, compact oil filter that can conveniently be used with a number of different deep frying vats.
It is a further object of the invention to provide a filtering machine requiring a minimum of maintenance while providing consistently high efficiency.